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Tree-Ring Research, Vol. 58, No. 01-02 (2002)

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Tree-Ring Research is the peer-reviewed journal of the Tree-Ring Society. The journal was first published in 1934 under the title Tree-Ring Bulletin. In 2001, the title changed to Tree-Ring Research.

The Tree-Ring Society and the Laboratory of Tree-Ring Research at the University of Arizona partnered with the University Libraries to digitize back issues for improved searching capabilities and long-term preservation. New issues are added on an annual basis, with a rolling wall of five years.

Dendrochronologists traditionally report the grit size on abrasive papers used to prepare surfaces for tree-ring analysis, but significant differences exist in the measured particle size ranges defined by the different systems (e.g. FEPA, ANSI, ISO, JIS, etc.) used worldwide. The systems themselves are also subject to change and discontinuation. We propose that dendrochronologists report (1) the standard used to manufacture the grit (e.g. ANSI in the U.S.), (2) the grade within the standard (e.g. 400-grit), and (3) the SI equivalent measurements of mean or included-range grit-size dimensions (e.g. 20.6-23.6 μm). For example, rather than reporting our use of 60-grit or 400-grit, we would instead report ANSI 60-grit (250- 297 μm) and ANSI 400-grit (20.6-23.6 μm) sandpaper. Adopting SI equivalents will help standardize our methods by providing concise, replicable information about surface preparation, considered by many the most crucial step for helping to define clear ring boundaries and to ensure successful crossdating.

High-resolution paleoclimatic data for West Africa are needed to provide context for contemporary climatic and ecological dynamics. Six hundred trees (22 botanical families, 43 genera and over 70 species) from semi-arid West Africa were evaluated for their suitability for dendrochronological research; specifically ring development. The samples were classified as 'potentially useful', 'problematic', or 'poor' based on the presence and distinctiveness of annual rings, ability to achieve crossdating between radii using skeleton plots on at least some samples, circuit uniformity, ring wedging, and variability of ring widths. Samples were classified as potentially useful if (a) they exhibited distinctive annual rings that could be identified and counted with little uncertainty and be independently verified by a second person with little or no error, (b) crossdating between radii could be successfully achieved, at least on some samples, (c) the rings were generally consistent throughout the stem cross section, (d) ring wedging was minimal (in the relative sense) or absent, and (e) the ring widths were variable, indicating the possibility of climatic sensitivity. Seven species, including five from the Caesalpiniaceae family (Cassia sieberiana, Cordyla pinnata, Daniella oliveri, Isoberlinia doka, Tamarindus indica), and one each from Mimosaceae (Acacia seyal) and Verbenaceae (Gmelina arborea) families, that most closely satisfied these criteria were classified as 'potentially useful'. The 'problematic' category includes those samples that satisfied some of the criteria but for which greater diligence is required to detect rings. Eight species from three families were classified in this category. Finally those samples on which ring detection appears futile given current methods and techniques were classified as 'poor'. Most of the samples classified as 'potentially useful' belong to three botanical families, Caesalpiniaceae, Mimosacae, and Verbenaceae. These results are consistent with the findings of other studies, and therefore support further investigation of the potential of West African trees for tree-ring analysis focusing on these families. Furthermore, inability to crossdate between trees and to explain several ring anatomical features underscores the pressing need for comprehensive field studies of cambial activity during the growing season, and for the identification of dormant seasons. This requirement, and other difficulties discussed suggest a need for increasing the local dendrochronological expertise in West Africa.

A 345-year (AD 1656-2000) ring-width chronology of common yew (Taxus baccata L.) from the western Himalaya has been prepared. This provides the first record of a well crossdated ring-width chronology of yew from the Himalayan region, India. The mean temperature of the premonsoon (March-June) season has an indirect relationship with tree growth. The yew chronology is also significantly correlated with an Abies pindrow chronology prepared from the same stand as well as A. spectabilis from the treeline zone of an adjacent site. Such a significant relationship indicates the good potential of yew for dendroclimatic studies in the Himalayan region.

Dendrochronological methods were used to date hail injuries in tree rings of six mountain pines (Pinus mugo var. uncinata) at a site in central Switzerland. Annually dated injuries (1939-1996) were in 89% of the cases attributable to years with severe regional hailstorm occurrence (1957-1996). Days with severe hailstorms were successfully dated in either the earlywood and /or latewood portions of a tree ring in a given year. Tree rings provide an alternative proxy to existing data for reconstructing past severe hailstorm occurrence.

Changes in mean earlywood vessel areas in mature Quercus macrocarpa were analyzed to determine possible sources of bias in paleoflood records derived from anatomical tree-ring signatures. Tree-ring cores were collected at intervals along the vertical axis of four Q. macrocarpa in a flood-prone stand near the Red River in Manitoba. The WinCELL PRO image analysis system was used to measure mean vessel areas in each annual ring. Most cores displayed a pronounced juvenile increase in mean vessel area before stabilizing between 40 and 60 years. The lowest samples from several trees contain rings with anomalously small mean vessel areas that are coincident with high-magnitude Red River floods in 1950 and 1997. The anatomical response of Q. macrocarpa appears to be conditional on the relative timing of earlywood development and flooding. Flood signatures are most strongly developed near the tree base and become less evident up the trunk. Most signatures disappear between one and three meters in height. Differences in flood response between trees are likely caused by internal differences rather than hydrological or topographic factors. Paleoflood studies based on samples obtained exclusively at breast height may miss some anatomical flood signatures and underestimate flood frequency relative to earlier intervals.

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